"""
Better Move Sprite With Keyboard

Simple program to show moving a sprite with the keyboard.
This is slightly better than sprite_move_keyboard.py example
in how it works, but also slightly more complex.

Artwork from https://kenney.nl

If Python and Arcade are installed, this example can be run from the command line with:
python -m arcade.examples.sprite_move_keyboard_better

用键盘更好地移动Sprite

显示用键盘移动角色的简单程序。
这在工作方式上比sprite_move_keyboard.py示例稍微好一些，但也稍微复杂一些。


"""

import arcade

SPRITE_SCALING = 0.5

WINDOW_WIDTH = 1280
WINDOW_HEIGHT = 720
WINDOW_TITLE = "Better Move Sprite with Keyboard Example"

MOVEMENT_SPEED = 5


class Player(arcade.Sprite):

    def update(self, delta_time: float = 1/60):
        """ Move the player """
        # Move player.
        # Remove these lines if physics engine is moving player.
        # 根据速度移动位置
        self.center_x += self.change_x
        self.center_y += self.change_y

        # Check for out-of-bounds
        # 控制上下左右的边界（但并不控制速度）
        if self.left < 0:
            self.left = 0
        elif self.right > WINDOW_WIDTH - 1:
            self.right = WINDOW_WIDTH - 1

        if self.bottom < 0:
            self.bottom = 0
        elif self.top > WINDOW_HEIGHT - 1:
            self.top = WINDOW_HEIGHT - 1


class GameView(arcade.View):
    """
    Main application class.
    """

    def __init__(self):
        """
        Initializer
        """

        # Call the parent class initializer
        super().__init__()

        # Variables that will hold sprite lists
        self.player_list = None

        # Set up the player info
        self.player_sprite = None

        # Track the current state of what key is pressed
        self.left_pressed = False
        self.right_pressed = False
        self.up_pressed = False
        self.down_pressed = False

        # Set the background color
        self.background_color = arcade.color.AMAZON

    def setup(self):
        """ Set up the game and initialize the variables. """

        # Sprite lists
        self.player_list = arcade.SpriteList()

        # Set up the player
        # 初始化玩家精灵，包括图像及大小，中心位置。并将玩家精灵装载到精灵列表中
        self.player_sprite = Player(
            ":resources:images/animated_characters/female_person/femalePerson_idle.png",
            scale=SPRITE_SCALING,
        )
        self.player_sprite.center_x = 50
        self.player_sprite.center_y = 50
        self.player_list.append(self.player_sprite)

    def on_draw(self):
        """ Render the screen. """

        # Clear the screen
        self.clear()

        # Draw all the sprites.
        self.player_list.draw()

    def update_player_speed(self):

        # Calculate speed based on the keys pressed
        # 更新玩家速度（该方法是直来直去的速度更新，并没有考虑加速度和摩擦力）
        self.player_sprite.change_x = 0
        self.player_sprite.change_y = 0

        if self.up_pressed and not self.down_pressed:
            self.player_sprite.change_y = MOVEMENT_SPEED
        elif self.down_pressed and not self.up_pressed:
            self.player_sprite.change_y = -MOVEMENT_SPEED
        if self.left_pressed and not self.right_pressed:
            self.player_sprite.change_x = -MOVEMENT_SPEED
        elif self.right_pressed and not self.left_pressed:
            self.player_sprite.change_x = MOVEMENT_SPEED

    def on_update(self, delta_time):
        """ Movement and game logic """

        # Call update to move the sprite
        # If using a physics engine, call update player to rely on physics engine
        # for movement, and call physics engine here.
        self.player_list.update(delta_time)

    def on_key_press(self, key, modifiers):
        """Called whenever a key is pressed. """

        # 一种控制玩家精灵移动的方法，是将操作键的信息传给精灵（精灵在update时根据操作键信息更新数据），而不是直接调用精灵方法
        if key == arcade.key.UP:
            self.up_pressed = True
            self.update_player_speed()
        elif key == arcade.key.DOWN:
            self.down_pressed = True
            self.update_player_speed()
        elif key == arcade.key.LEFT:
            self.left_pressed = True
            self.update_player_speed()
        elif key == arcade.key.RIGHT:
            self.right_pressed = True
            self.update_player_speed()

    def on_key_release(self, key, modifiers):
        """Called when the user releases a key. """

        if key == arcade.key.UP:
            self.up_pressed = False
            self.update_player_speed()
        elif key == arcade.key.DOWN:
            self.down_pressed = False
            self.update_player_speed()
        elif key == arcade.key.LEFT:
            self.left_pressed = False
            self.update_player_speed()
        elif key == arcade.key.RIGHT:
            self.right_pressed = False
            self.update_player_speed()


def main():
    """ Main function """
    # Create a window class. This is what actually shows up on screen
    window = arcade.Window(WINDOW_WIDTH, WINDOW_HEIGHT, WINDOW_TITLE)

    # Create and setup the GameView
    game = GameView()
    game.setup()

    # Show GameView on screen
    window.show_view(game)

    # Start the arcade game loop
    arcade.run()


if __name__ == "__main__":
    main()